Food-related: Food poisoning (which has symptoms like those of stomach/gut flu),
food allergies, eating excessive food, or
gas production – any of these can cause
bloating and temporary discomfort.
Usually the onset is rapid after eating.

Poisoning: This
can range from simple problems (such as eating soap) to more serious issues like
swallowing
iron pills, magnets, coins, botulism from spoiled food, or an overdose of medications
(such as
acetaminophen poisoning [Tylenol]).

Surgical problems: These include appendicitis or blockage of the bowels.

Medical causes: Things outside the abdomen can cause abdominal pain. For example, a child can have abdominal pain from complications of diabetes or from a black widow spider bite.